• Motion occurs when there is a change in position of an object with respect to a reference starting point.
• The final position of an object is determined by measuring the change in position and direction of the segments along a trip. The following terms are used to describe and determine motion:

​Position

• Position is the location of an object.
• An object changes position if it moves relative to a reference point (starting point).
• The change in position is determined by the distance and direction of an object’s change in position from the starting point (displacement).

Direction

• Direction is the line, or path along which something is moving, pointing, or aiming.
• Direction is measured using a reference point with terms such as up, down, left, right, forward, backward, toward, away from, north, south, east, or west.

Speed

• The slope (slant or angle) of the line can tell the relative speed of the object.
• When the slope of the line is steep, the speed is faster than if the slope were flatter.
• When the slope of the line is flatter, the speed is slower.
• When the slope of the line is horizontal to the x-axis, the speed is zero (the object is not moving).

Position-Time Graphs

• A graph used to show a change in an object’s location over time.
• For this type of graph, time (the independent variable) is plotted on the x-axis and the position (the dependent variable) is plotted on the y-axis.

Different types of graphs representing changes in speed and direction.